i40e: fix an uninitialized variable bug

We removed this initialization but it is required.  Let's put it back.

Fixes: 895106a5 ('i40e: trivial fixes')
Signed-off-by: Dan Carpenter <dan.carpenter@oracle.com>
Tested-by: Andrew Bowers <andrewx.bowers@intel.com>
Signed-off-by: Jeff Kirsher <jeffrey.t.kirsher@intel.com>